Characteristics of study subjects
| Normal (n = 11) | Idiopathic cough (n = 19) | Explained cough (n = 14) | |
|---|---|---|---|
| Data expressed as mean (SE) except †geometric mean (log SE). | |||
| VAS = visual analogue score (0–100 mm = worst symptom); C2 and C5 = concentration of capsaicin causing two and five coughs, respectively. | |||
| *p<0.001 (ANOVA). | |||
| Age (years) | 52 (5) | 54 (2) | 55 (4) |
| Male (%) | 3 (27) | 4 (21) | 5 (36) |
| Cough VAS (mm) | 0 | 57 (4) | 51 (5) |
| Age of onset of cough (years) | 47 (3) | 52 (4) | |
| Cough duration (years) | 0 | 7 (3) | 8 (6) |
| FEV1 (% predicted) | 111 (5) | 104 (4) | 101 (3) |
| FEV1/FVC% | 80 (2) | 80 (1) | 77 (2) |
| PC20FEV1 >8 mg/ml (n (%)) | 11 (100) | 19 (100) | 10 (71) |
| C2 (μmol/l)† | 47.9 (0.2) | 2.2 (0.2)* | 2.2 (0.2)* |
| C5 (μmol/l)† | 416.9 (0.1) | 6.9 (0.2)* | 11.5 (0.3)* |
| Nitric oxide (ppb)† | 1.8 (0.2) | 2.2 (0.1) | 5.4 (0.1) |
| Positive allergen specific IgE (n (%)) | 1 (9) | 3 (16) | 4 (29) |
| Blood lymphocytes (× 109 cells/l) | 2.1 (0.2) | 1.8 (0.1) | 2.2 (0.1) |